Lasers have been widely used in various fields such as industry, aesthetic medicine, scientific research, and so on. Laser construction is mainly composed of three main parts: an optical resonator, a gain medium, and an energy pumping device (usually referred to as a pumping source). As to a high power ultrashort pulse laser system such as a picosecond or femtosecond laser, it requires a greater variety of optical components for modulating a laser pulse, thereby achieving the requirements of ultra-short pulse and high power.
The conventional ultrashort pulse laser system includes multiple optical functional modules, such as a Ti:sapphire (titanium-sapphire) oscillator, a pulse stretcher, a pulse amplifier, a pulse compressor, and so on, as described, for instance, in an article by S. Backus et al, entitled “Ti:sapphire amplifier producing millijoule-level, 21-fs pulses at 1 kHz” published in Optics Letters, Vol. 20, Issue 19, pp. 2000-2002 (1995). Specifically, each optical module includes multiple optical components. For example, the multi-pass amplifier described in the article includes a gain crystal, concave mirrors, a stimulating light source, mirrors, etc. In addition, the high power picosecond laser can be generated by using a regenerative amplifier, as described in the article entitled “A picosecond thin-rod Yb:YAG regenerative laser amplifier with the high average power of 20 W” by S Matsubara et al, published in Laser Phys. Lett. 10, 055810 (2013). The regenerative amplifier includes a laser oscillator, a Pockels Cell, a polarizer, lenses, and so on.
However, because these ultrashort pulse laser systems need to take up a lot of space for setting up the above-mentioned optical modules on an optical bench, the conventional ultrashort pulse laser systems have a shortcoming of vast bulk, and hence they are difficult to commercialize. Moreover, due to the high power requirements, a large quantity of heat is produced. However, the laser oscillator is very sensitive to the temperature. The waste heat generated by the amplifier will influence the laser oscillator, and results in an unstable laser output.